Position determining apparatus for coordinate machine

Abstract

A programmable device which produces a plurality of outputs is connected to a controller having less input ports than there are outputs to be received by the controller. To overcome this problem the controller is programmed to send different signals to the device, one at a time, upon receipt of a particular one of which, the device sends back a corresponding one of its outputs. In the specific example described the signals are different sequences of timing pulses.

What is claimed is:  
     
       1. A measuring system for a machine tool, comprising: 
       a machine tool controller having at least one input port and having a controller timer; and  
       a programmable measurement device having a measurement signal output receivable by the machine tool controller at the at least one input port,  
       wherein the controller timer is operable to produce different timed sequences of signal for selective input to the device,  
       wherein the device is operable to receive each signal input from the controller, and to vary its measurement signal output in response to the timing of that signal input, and  
       wherein the number of measurement signal outputs of the device exceeds the number of input ports.  
     
     
       2. A measuring system as claimed in  claim 1 , wherein the function of the measurement device is changeable in response to the timing of the signal input to the device and the function of the measurement device varies the measurement signal output. 
     
     
       3. A measuring system as claimed in  claim 1 , wherein the measurement device comprises a toolsetting apparatus including a light emitting unit which emits a beam of light and a light detecting unit at which the light beam is detected. 
     
     
       4. A measuring system as claimed in  claim 3 , wherein the toolsetting apparatus has a plurality of modes of operation each selectable by a different signal input to the apparatus and each for causing the measurement output signal of the apparatus to vary. 
     
     
       5. A method of measuring on a machine tool having a machine tool controller including at least one input port and a timer; 
       a programmable measurement device including a measurement signal output receivable by the machine tool controller at the at least one input port, and the number of measurement signal outputs of the device exceeding the number of input ports, the method comprising the steps, in any suitable order, of:  
       operating the timer to produce different timed sequences of signal for selective input to the device;  
       operating the device to receive each signal input from the controller; and  
       operating the device so as to vary its measurement signal output in response to the timing of the signal input from the controller.